轧制变形对Al-5Zn-3Mg-1Cu-0.12Zr合金厚板剥蚀淬火敏感性的影响

Effect of Rolling Deformation on Quench Sensitivity to Exfoliation Corrosion of Thick Al-5Zn-3Mg-1Cu-0.12Zr Alloy Plate

采用末端淬火试验、剥落腐蚀浸泡试验、光学显微镜和透射电子显微镜等方法,研究了轧制变形量对Al-5Zn-3Mg-1Cu-0.12Zr铝合金厚板剥落腐蚀敏感性的影响.结果表明:该合金板材的抗剥落腐蚀性能随冷却速率减小而降低,降低程度随热轧变形量的增加而提高,即剥落腐蚀淬火敏感性增加;变形量由56%增加至91%,在冷却速率为2160℃/min时,剥落腐蚀等级都为P级,在冷却速率为100℃/min时,剥落腐蚀等级由EA级增加至ED级;变形量分别为56%、72%、81%和91%时,在冷却速率分别大于100、159、209和320℃/min的区域,合金剥落腐蚀等级达到或优于EA级;在相同轧制变形量下,冷却速率的减小会使合金晶界无沉淀析出带宽化,导致合金抗剥蚀性能变差.

This paper deals with the effect of rolling deformation on the quench sensitivity to the exfoliation corro- sion （EXCO） of thick Al-SZn-3Mg-1Cu-0. 12Zr alloy plates by means of end-quenching testing, corrosion immer- sion testing, optical microscopy and transmission electron microscopy. The results show that （1） the resistance to EXCO of the plate decreases with the decrease in with the increase in hot rolling deformation, which cooling rate, and the decrement of EXCO resistance increases means that there exists an increasing quench sensitivity to EX- CO; （2） when the rolling deformation ranges from 56% to 91% , the exfoliation corrosion levels of all the samples are P at a quench rate of 2160 ℃/min, while the level varies from EA to ED at a quench rate of 100 ℃/min; （3） when the rolling deformation is 56%, 72%, 81% and 91% , the exfoliation corrosion level is EA or deeper than EA at the quench rates of more than 100, 159, 209 and 320 ℃/min; and （4） under a constant roiling deforma- tion, the precipitate free zone will be widened with the decrease of quench rate, which may result in the degradation of the exfoliation corrosion resistance.